Born in Bolzano, South Tyrol, Guerra started his career at Veneto club Hellas Verona.
He made his Serie A debut on 15 September 1991, against Internazionale; he came on as a substitute for Marino Magrin in the 59th minute.
He made his second appearance for Verona on 3 November 1991, against Parma, replacing Paolo Piubelli in the 53rd minute; the match ended in a 1–1 draw.
In the 1993–94 season, Guerra returned to Verona, where he became a regular starter for the club in Serie B.
[1] On 22 August 2001, Guerra left for Serie B newcomers Palermo in a co-ownership deal, where he played 33 times in the league.